From 7f66590677e7f3e461fc88ab5d26e11981b0f05f Mon Sep 17 00:00:00 2001 From: Slawek Kaplonski Date: Mon, 23 Aug 2021 13:01:37 +0200 Subject: [PATCH] Remove dhcp_extra_opt value after first newline character Passing newline to the dnsmasq may cause security issues, especially that in case of Neutron that dhcp options' values are controlled by cloud users. This patch removes everything what is after first newline character in the dhcp_extra_opt's values before passing them to dnsmasq. Closes-Bug: #1939733 Change-Id: Ifeaf258f0b5ea86f25620ac4116d618980a7272e --- neutron/agent/linux/dhcp.py | 7 ++++--- neutron/tests/unit/agent/linux/test_dhcp.py | 7 ++++++- ...wline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml | 6 ++++++ 3 files changed, 16 insertions(+), 4 deletions(-) create mode 100644 releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml diff --git a/neutron/agent/linux/dhcp.py b/neutron/agent/linux/dhcp.py index 84293f8841..16404df130 100644 --- a/neutron/agent/linux/dhcp.py +++ b/neutron/agent/linux/dhcp.py @@ -1326,10 +1326,11 @@ class Dnsmasq(DhcpLocalProcess): elif not option.isdigit(): option = 'option:%s' % option if extra_tag: - tags = ('tag:' + tag, extra_tag[:-1], '%s' % option) + tags = ['tag:' + tag, extra_tag[:-1], '%s' % option] else: - tags = ('tag:' + tag, '%s' % option) - return ','.join(tags + args) + tags = ['tag:' + tag, '%s' % option] + + return ','.join(tags + [v.split("\n", 1)[0] for v in args]) @staticmethod def _convert_to_literal_addrs(ip_version, ips): diff --git a/neutron/tests/unit/agent/linux/test_dhcp.py b/neutron/tests/unit/agent/linux/test_dhcp.py index 261bc44386..c05f0e472f 100644 --- a/neutron/tests/unit/agent/linux/test_dhcp.py +++ b/neutron/tests/unit/agent/linux/test_dhcp.py @@ -230,6 +230,9 @@ class FakeV6PortExtraOpt(object): self.extra_dhcp_opts = [ DhcpOpt(opt_name='dns-server', opt_value='ffea:3ba5:a17a:4ba3::100', + ip_version=constants.IP_VERSION_6), + DhcpOpt(opt_name='malicious-option', + opt_value='aaa\nbbb.ccc\n', ip_version=constants.IP_VERSION_6)] @@ -2911,7 +2914,9 @@ class TestDnsmasq(TestBase): exp_opt_data = ('tag:subnet-eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee,' 'option6:domain-search,openstacklocal\n' 'tag:port-hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh,' - 'option6:dns-server,ffea:3ba5:a17a:4ba3::100').lstrip() + 'option6:dns-server,ffea:3ba5:a17a:4ba3::100\n' + 'tag:port-hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh,' + 'option6:malicious-option,aaa').lstrip() dm = self._get_dnsmasq(FakeV6NetworkStatelessDHCP()) dm._output_hosts_file() dm._output_opts_file() diff --git a/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml b/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml new file mode 100644 index 0000000000..d2a8c2f68b --- /dev/null +++ b/releasenotes/notes/fix-newline-chars-in-dhcp-extra-options-bf86d30371556d63.yaml @@ -0,0 +1,6 @@ +--- +security: + - | + Fix `bug 1939733 `_ by + dropping from the dhcp extra option values everything what is after first + newline (``\n``) character before passing them to the dnsmasq. -- 2.33.0